Having issues with the original tachs in my 87 SR1. From what I read and a few phone calls. The original tachs can be used with msd box and coil. I tested the grey wire from the msd box and it reading the proper voltage. I have good ground and power... I have 4 VDO factory tachs... two claimed to be good take offs... any insight would be great . Thanks

All I ever hear is nightmares from msd. What was wrong with the bullet proof thunderbolt?

Never had it... I did a full repower with 502s . The boat runs amazing. Just having a tach issue. I could replace them with an aftermarket style... I kinda like the old school VDO factory look . I can't be the only person that did this combo

What does the tach do ?

I installed MSD boxes on my 1991 272 SR1. You need an adapter to make them work.
PN 8910 if carb,
PN 8910-EIS if injected.
By the way, one of my brand new MSD boxes died within 5 hours of operation.

I think the MSD problem is hit or miss.Ive been running mine for 4 years without any issue. That being said,I plan to go with a Daytona box and Thunderbolt IV at the end of the season. I have read too many posts cursing the MSD boxes to trust mine any longer. Also the weights and springs in the pro billet distributor are easily corroded and require regular attention. When idle speed wont return to set RPM it's time to change the springs.Reliability is what I'm interested in above else.

Thanks.. that's what I came up with. I guess the first call to MSD the guy told me no... plus the directions said no too... .. well on that note the second call to MSD they said yes for adapers

I had the tach adapter box and msd. The stock tach never really seemed accurate no matter what i did. Low end rpm seemed a few 100 off but the top end seemed close. After my msd burned up the first time i built a spare to get me home in case it happened again. The spare was based off a stock gm hei module. I installed male and female spade connectors so it could be swapped to the spare easily. All in all it cost me about $30 and added tons of piece of mind. Ill look around and see if i can find the schematic again.

Jim I just when through this I picked up a tach adapter an 8910 , and now the tach works I have an msd 6 al I believe .